Clockwise versus counterclockwise rotation in bimaxillary surgery: 3D analysis of facial soft tissue outcomes.

PURPOSE: This study aimed to compare facial 3D soft tissue changes in subjects with Class III deformities who underwent bimaxillary clockwise (CW) and counterclockwise (CCW) rotational orthognathic surgery. METHODS: Asian Class III subjects who completed bimaxillary surgical orthodontic treatments were enrolled and categorized into CW and CCW groups based on maxillary occlusal plane alterations. Preoperative and 9-month follow-up cone-beam computed tomography (CBCT) and 3D stereophotogrammetry were obtained, superimposed, and quantified for skeletal movements and soft tissue changes in six facial regions. Inverse probability of treatment weighting (IPTW) adjusted for potential confounding factors. RESULTS: Thirty-seven subjects were included (CW group, n = 20; CCW group, n = 17). Postsurgical chin volume significantly reduced in the CW group compared to the CCW group (mean difference 6362 mm3; p = 0.037), and intergonial width significantly decreased in the CW group (mean difference 6.2 mm; p = 0.005). The postoperative alar width increased by 1.04 mm and 1.22 mm in the CW and CCW groups, respectively (p = 0.70). However, these changes were not significantly correlated to the direction of MMC pitch. CONCLUSION: Clockwise rotation of the bimaxillary complex demonstrated a significant advantage in reducing chin volume and intergonial width compared to counterclockwise rotation, leading to a reduced frontal lower face width among Asian Class III subjects.

Longitudinal Three-Dimensional Stereophotogrammetric Growth Analysis in Infants with Unilateral Cleft Lip and Palate from 3 to 12 Months of Age.

This longitudinal study aimed to evaluate facial growth and soft tissue changes in infants with complete unilateral cleft lip, alveolus, and palate (CUCLAP) at ages 3, 9, and 12 months. Using 3D images of 22 CUCLAP infants, average faces and distance maps for the entire face and specific regions were created. Color-coded maps highlighted more significant soft tissue changes from 3 to 9 months than from 9 to 12 months. The first interval showed substantial growth in the entire face, particularly in the forehead, eyes, lower lip, chin, and cheeks (p < 0.001), while the second interval exhibited no significant growth. This study provides insights into facial soft tissue growth in CUCLAP infants during critical developmental stages, emphasizing substantial improvements between 3 and 9 months, mainly in the chin, lower lip, and forehead. However, uneven growth occurred in the upper lip, philtrum, and nostrils throughout both intervals, with an overall decline in growth from 9 to 12 months. These findings underscore the dynamic nature of soft tissue growth in CUCLAP patients, highlighting the need to consider these patterns in treatment planning. Future research should explore the underlying factors and develop customized treatment interventions for enhanced facial aesthetics and function in this population.

What is the impact of miniscrew-assisted rapid palatal expansion on the midfacial soft tissues? A prospective three-dimensional stereophotogrammetry study.

OBJECTIVES: To evaluate the midfacial soft tissue changes of the face in patients treated with miniscrew-assisted rapid palatal expansion (MARPE). MATERIALS AND METHODS: 3D facial images and intra-oral scans (IOS) were obtained before expansion (T0), immediately after completion of expansion (T1), and 1 year after expansion (T2). The 3D images were superimposed and two 3D distance maps were generated to measure the midfacial soft tissue changes: immediate effects between timepoints T0 and T1 and overall effects between T0 and T2. Changes of the alar width were also measured and dental expansion was measured as the interpremolar width (IPW) on IOS. RESULTS: Twenty-nine patients (22 women, 7 men, mean age 25.9 years) were enrolled. The soft tissue in the regions of the nose, left of philtrum, right of philtrum, and upper lip tubercle demonstrated a statistically significant anterior movement of 0.30 mm, 0.93 mm, 0.74 mm, and 0.81 mm, respectively (p < 0.01) immediately after expansion (T0-T1). These changes persisted as an overall effect (T0-T2). The alar width initially increased by 1.59 mm, and then decreased by 0.08 mm after 1 year, but this effect was not significant. The IPW increased by 4.58 mm and remained stable 1 year later. There was no significant correlation between the increase in IPW and alar width (r = 0.35, p = 0.06). CONCLUSIONS: Our findings indicate that MARPE results in significant but small changes of the soft tissue in the peri-oral and nasal regions. However, the clinical importance of these findings is limited. CLINICAL RELEVANCE: MARPE is an effective treatment modality to expand the maxilla, incurring only minimal and clinically insignificant changes to the midfacial soft tissues.

The Prediction Accuracy of Digital Orthodontic Setups for the Orthodontic Phase before Orthognathic Surgery.

The purpose of this study was to verify whether pre-treatment digital setups can accurately predict the tooth positions after presurgical orthodontic treatment has been performed in a 3-dimensional way. Twenty-six patients who underwent a combined orthodontic-orthognathic surgical treatment were included. Pre-treatment digital dental models were merged with cone beam computed tomography (CBCT) scans. One operator fabricated virtual setups to simulate the tooth movements of the presurgical orthodontic treatment. Prior to surgery, digital dental models were merged with the CBCT scans. Differences between de virtual setups and the presurgical dental models were calculated using linear mixed model analyses. Differences in tooth displacements exceeding the boundaries of clinical acceptance (>2 degrees for rotations and >0.6 mm for translations) were found in 75% of the rotational and 52% of translational mean differences in the maxilla and in 74% of the rotational mean differences and 44% of the translational mean differences in the mandible. Significant differences were found for all tooth types and in all tooth displacement directions with significant effects of extractions and surgically assisted rapid maxillary expansion (SARME) procedures. The accuracy of the digital setup is still too limited to correctly simulate the presurgical orthodontic treatment.

A semi-automatic three-dimensional technique using a regionalized facial template enables facial growth assessment in healthy children from 1.5 to 5.0 years of age.

Objectives: To develop a semi-automatic technique to evaluate normative facial growth in healthy children between the age of 1.5 and 5.0 years using three-dimensional stereophotogrammetric images. Materials and Methods: Three-dimensional facial images of healthy children at 1.5, 2.0, 2.5, 3.0, 4.0 and 5.0 years of age were collected and positioned based on a reference frame. A general face template was used to extract the face and its separate regions from the full stereophotogrammetric image. Furthermore, this template was used to create a uniform distributed mesh, which could be directly compared to other meshes. Average faces were created for each age group and mean growth was determined between consecutive groups for the full face and its separate regions. Finally, the results were tested for intra- and inter-operator performance. Results: The highest growth velocity was present in the first period between 1.5 and 2.0 years of age with an average of 1.50 mm (±0.54 mm) per six months. After 2.0 years, facial growth velocity declined to only a third at the age of 5.0 years. Intra- and inter-operator variability was small and not significant. Conclusions: The results show that this technique can be used for objective clinical evaluation of facial growth. Example normative facial averages and the corresponding facial growth between the age 1.5 and 5.0 years are shown. Clinical Relevance: This technique can be used to collect and process facial data for objective clinical evaluation of facial growth in the individual patient. Furthermore, these data can be used as normative data in future comparative studies.

Operator Performance of the Digital Setup Fabrication for Orthodontic-Orthognathic Treatment: An Explorative Study.

The purpose of this study was to explore the operator performance of the fabrication of digital orthodontic setups integrated into cone beam computed tomography (CBCT) scans. Fifteen patients who underwent a combined orthodontic-orthognathic surgical treatment were included. The pre-treatment digital dental models and CBCT scans were fused, and four operators made virtual setups twice for all patients. Differences between the virtual setups were calculated by recording tooth crown movement from the pre-treatment model to the virtual setup. To examine performance, Pearson's correlation coefficients, duplicate measurement errors, and inter-operator differences were calculated. For intra-operator performance, correlation values varied among tooth types, with mean correlation values from 0.66 to 0.83 for the maxilla and 0.70 to 0.83 for the mandible. For inter-operator performance, mean correlation values varied from 0.40 to 0.87 for the maxilla and from 0.44 to 0.80 for the mandible. Rotational mean differences exceeded the range of clinical acceptance (>2 degrees) at 18% for the maxilla and 20.8% for the mandible, and translational mean differences exceeded the range of clinical acceptance (0.6 mm) at 9.7% and 26% for the maxilla and mandible, respectively. The intra- and inter-operator performance of digital orthodontic setup construction for virtual three-dimensional orthognathic planning shows significant errors.

Highly variable rate of orthodontic tooth movement measured by a novel 3D method correlates with gingival inflammation.

OBJECTIVES: Individual orthodontic treatment duration is hard to predict. Individual biological factors are amongst factors influencing individual rate of orthodontically induced tooth movement (OTM). The study aim is to determine the rate of OTM by a novel 3D method and investigate parameters that may predict the rate of tooth movement. MATERIALS AND METHODS: In this prospective cohort study, rate of OTM was determined from 90 three-dimensional intra-oral scans in 15 patients (aged 12-15) undergoing orthodontic treatment. For each patient, intra-oral scans were taken every week for up to 6 weeks (T0-T5). The teeth were segmented from the scans and the scans were superimposed on the palatal rugae. The rate of OTM was calculated for each tooth. Other parameters were gingival inflammation, contact-point displacement and the biological markers, matrix metalloproteinases (MMP), MMP-9 and MMP-2 in gingival crevicular fluid (GCF). RESULTS: Our study showed a high variation in the rate of OTM, varying from 0.15 to 1.24 mm/week. Teeth in the anterior segment tended to move more compared with the posterior segment. The contact point displacement and gingival inflammation varied greatly amongst the patients. The MMPs measured did not correlate with tooth movement. However, the gingival inflammation index showed a significant correlation with OTM. Future studies should include other biological markers related to bone-remodeling. CONCLUSION: This novel and efficient 3D method is suitable for measuring OTM and showed large individual variation in rate of OTM. CLINICAL RELEVANCE: Patients show different rates of OTM. The rate of OTM in an individual patient can provide guidance in timing of follow-up appointments.

The effect of lip closure on palatal growth in patients with unilateral clefts.

OBJECTIVES: The objective of this study was to compare maxillary dimensions and growth in newborns with Complete Unilateral Cleft Lip and Palate (UCLP) to healthy newborns before and after cheiloplasty. Additionally, a palatal growth curve is constructed to give more information about the natural growth before surgical intervention. METHODS: Twenty-eight newborns with complete UCLP were enrolled in this study. Multiple plaster-casts of each child during their first year were collected and grouped in before and after cheiloplasty. A previous developed semi-automatic segmentation tool was used to assess the maxillary dimensions and were compared to a healthy control group. Z-scores were calculated to indicate differences between the two populations and if cheiloplasty had influence on maxillary growth. Furthermore, the prediction model created in a previous study was used to indicate differences between predictions and the outcome in UCLP measurements. The analysis was tested for inter- and intra-observer variability. RESULTS: Results show differences in alveolar and palatal shape in UCLP patients in comparison with healthy controls. Prior to cheiloplasty an increased width and alveolar length was observed while the palatal depth was decreased. After cheiloplasty the widths moved towards normal but were still significantly larger. CONCLUSION: Infants with unilateral cleft lip and palate show a wider maxillary arch in comparison with the control population. Initial treatment has most influence on the width of the arch, which decreased towards normal.

Three-dimensional characterization of mandibular asymmetry in craniofacial microsomia.

OBJECTIVES: This study aimed to investigate the three-dimensional (3D) mandibular asymmetry in craniofacial microsomia (CFM) and its association with the Pruzansky-Kaban classification system. MATERIALS AND METHODS: Cone-beam computed tomography images of 48 adult CFM cases were collected. The asymmetry of the mandibular body and ramus was analyzed with 3D landmarks. The mirrored mandibular model was registered on the original model, yielding a color-coded distance map and an average distance (i.e., asymmetry score) to quantify the overall mandibular asymmetry. RESULTS: The lengths of the mandibular body and ramus were significantly shorter on the affected than the contralateral side (p < 0.001). The ANB (p = 0.009), body and ramal lengths (both p < 0.001), and body and ramal length asymmetry (both p < 0.05) were significantly different between mild (types I/IIA) and severe (types IIB/III) cases. The mandibular asymmetry score correlated with mandibular body length asymmetry (r = 0.296, p = 0.046). CFM mandibles showed high variability in shape asymmetry. CONCLUSIONS: CFM patients showed distinct body and ramal length asymmetries. In severe cases, mandibles were smaller, more retruded, and more asymmetric in length. The mandibular shape asymmetry was highly variable regardless of the Pruzansky-Kaban types, being a determinant in the extent of overall mandibular asymmetry. CLINICAL RELEVANCE: The 3D morphologic analysis provides better insights into real mandibular asymmetry. Although the Pruzansky-Kaban classification was applied, high individual variability of the mandibular morphology still existed within the types. Therefore, individualized analyses and treatment plans for CFM patients are highly recommended.

A new segmentation algorithm for measuring CBCT images of nasal airway: a pilot study.

BACKGROUND: Three-dimensional (3D) modeling of the nasal airway space is becoming increasingly important for assessment in breathing disorders. Processing cone beam computed tomography (CBCT) scans of this region is complicated, however, by the intricate anatomy of the sinuses compared to the simpler nasopharynx. A gold standard for these measures also is lacking. Previous work has shown that software programs can vary in accuracy and reproducibility outcomes of these measurements. This study reports the reproducibility and accuracy of an algorithm, airway segmentor (AS), designed for nasal airway space analysis using a 3D printed anthropomorphic nasal airway model. METHODS: To test reproducibility, two examiners independently used AS to edit and segment 10 nasal airway CBCT scans. The intra- and inter-examiner reproducibility of the nasal airway volume was evaluated using paired t-tests and intraclass correlation coefficients. For accuracy testing, the CBCT data for pairs of nasal cavities were 3D printed to form hollow shell models. The water-equivalent method was used to calculate the inner volume as the gold standard, and the models were then embedded into a dry human skull as a phantom and subjected to CBCT. AS, along with the software programs MIMICS 19.0 and INVIVO 5, was applied to calculate the inner volume of the models from the CBCT scan of the phantom. The accuracy was reported as a percentage of the gold standard. RESULTS: The intra-examiner reproducibility was high, and the inter-examiner reproducibility was clinically acceptable. AS and MIMICS presented accurate volume calculations, while INVIVO 5 significantly overestimated the mockup of the nasal airway volume. CONCLUSION: With the aid of a 3D printing technique, the new algorithm AS was found to be a clinically reliable and accurate tool for the segmentation and reconstruction of the nasal airway space.

Validation of 3D documentation of palatal soft tissue shape, color, and irregularity with intraoral scanning.

OBJECTIVES: The purpose of this study was to assess the feasibility of 3D intraoral scanning for documentation of palatal soft tissue by evaluating the accuracy of shape, color, and curvature. MATERIALS AND METHODS: Intraoral scans of ten participants' upper dentition and palate were acquired with the TRIOS® 3D intraoral scanner by two observers. Conventional impressions were taken and digitized as a gold standard. The resulting surface models were aligned using an Iterative Closest Point approach. The absolute distance measurements between the intraoral models and the digitized impression were used to quantify the trueness and precision of intraoral scanning. The mean color of the palatal soft tissue was extracted in HSV (hue, saturation, value) format to establish the color precision. Finally, the mean curvature of the surface models was calculated and used for surface irregularity. RESULTS: Mean average distance error between the conventional impression models and the intraoral models was 0.02 ± 0.07 mm (p = 0.30). Mean interobserver color difference was - 0.08 ± 1.49° (p = 0.864), 0.28 ± 0.78% (p = 0.286), and 0.30 ± 1.14% (p = 0.426) for respectively hue, saturation, and value. The interobserver differences for overall and maximum surface irregularity were 0.01 ± 0.03 and 0.00 ± 0.05 mm. CONCLUSIONS: This study supports the hypothesis that the intraoral scan can perform a 3D documentation of palatal soft tissue in terms of shape, color, and curvature. CLINICAL RELEVANCE: An intraoral scanner can be an objective tool, adjunctive to the clinical examination of the palatal tissue.